Placodermi

views updated May 08 2018

Placodermi Class of archaic, jawed (gnathostome), and heavily armoured fish, which appeared in the Devonian and which were virtually extinct by the end of that period. They were rather diverse in body form. They all possessed a head shield formed by bony plates. Pectoral and pelvic fins appear to have been present. Most of them (e.g. Coccosteus) were bottom-dwelling fish, with a depressed body terminating in a heterocercal tail.

Placodermi

views updated May 14 2018

Placodermi A class of archaic, jawed (gnathostome), and heavily armoured fish, which appeared in the Devonian Period and which were virtually extinct by its end. They were rather diverse in body form. They all possessed a head shield formed by bony plates. Pectoral and pelvic fins appear to have been present. Most of them were bottom-dwelling, with a depressed body terminating in a heterocercal tail.